Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be accessed by various types of access terminals adapted to facilitate wireless communications, where multiple access terminals share the available system resources (e.g., time, frequency, and power). Examples of such wireless communications systems include code-division multiple access (CDMA) systems (e.g., CDMA2000), time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems and orthogonal frequency-division multiple access (OFDMA) systems.
Enhanced Voice-Data Optimized (EV-DO) Rev. A is an evolution of the CDMA2000 standard that can support high data rates and is deployed alongside a wireless carrier's voice services. EV-DO Rev. B is a multi-carrier evolution of the Rev. A specification and maintains the capabilities of EV-DO Rev. A. EV-DO Rev. B provides higher rates per carrier and higher rates by bundling multiple carriers together. Typical deployments may include 2 or 3 carriers for a peak rate of, for example, 14.7 Mbit/s. EV-DO Rev. B has reduced latency by using statistical multiplexing across channels, increased talk-time and standby time, reduced interference from the adjacent sectors especially to users at the edge of the cell signal which improves the rates that can be offered by using hybrid frequency re-use.
In conventional multi-carrier reverse-link (RL) transmission in EV-DO Rev. B, the waveform is generally driven through a single power amplifier at an access terminal. An issue with this configuration is that it can suffer from intermodulation distortion, resulting in a substantial amount of out-of-band interference, particularly when both carriers are configured with equal transmit powers. That is, with equal transmit power on dual carriers, out-of-band emission is the highest. This out-of-band interference can desense a receiver on the forward link, as well as violating certain spectral masks, that is, regulations on the amount of interference allowed on other bands.